For the last hundred plus years, storage bins and silos with flat-bottom floors have been used to store free flowing granular material, such as grain, salt, and sugar. In order to discharge the granular material out of the silo more effectively, many designs have been implemented with the flat-bottom floors of the storage bins and silos. The vast majority of these designs include the use of an exposed sweep auger for emptying the grain. Because one or more workers are usually needed to be inside the silo to carry out the unloading process while the exposed sweep auger is operating, the process of discharging the grain from the silo becomes dangerous.
Some prior art has used pneumatically movable flexible membranes to discharge the grain from the silo, such as a single flexible cup-shaped bag surrounding a central discharge opening. However, by only using a single bag to convey the grain within the silo, high pressure of air is maintained against the entire surface area of the cup-shaped bag during the unloading process, including a section of the bag not exposed to a load of bulk material. Consequently, a fully inflated segment of the bag forms during the initial stage of inflation and grows within the silo before full inflation of the bag is achieved. The fully inflated section creates an improper load balance along the surface of the bag, which places significant stresses on the silo wall, the exposed liner, and the clamp bar assemblies. These stresses may cause the silo wall to be pulled inward and seams on the liner to tear and rupture. Ultimately, the clamp bar assembly becomes bent and pulled away from the mounting surface along the silo wall, resulting in a leaky joint.
The inflated sections of the bag not exposed to bulk material also form folds between the segments of the liner during the initial stage of inflation. These folds trap the free flowing granular material, thereby hindering the flow of the granular material. As a result, the single flexible cup-shaped bag is not able to completely cleanout the granular material. Furthermore, a single bag design is difficult to be implemented in larger-sized silos, such as silos having diameters over 18 feet, because as the outer perimeter of the bag increases with respect to the diameter of the central discharge hole, the bag tends to fold, wrinkle and form a strong vacuum between the liner of the bag and the silo floor during deflation. The folding and wrinkling makes the liner return to the silo wall in an aligned manner virtually impossible.
Accordingly, there is a need for a discharge system that is scalable for larger-sized silos without the need for a sweep auger to convey the granular material.